Allergic contact dermatitis secondary to topical nitroglycerin.
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Administration, Topical↗
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Allergic contact dermatitis secondary to nitroglycerin in Nitro-Bid ointment.
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Administration, Topical↗
Beyond species trees: pervasive gene flow limits phylogenomic resolution in the diversification of Juniperus from the Qinghai-Tibet Plateau.
Understanding how lineages diversify despite persistent ancestral polymorphism and recurrent gene flow remains a central challenge in evolutionary biology. Juniperus distributed across the Qinghai-Tibet Plateau provide an ideal system for addressing this question because repeated geological uplift and climatic oscillations have likely promoted cycles of lineage divergence, range shifts, and secondary contact. Here, we combined approximately 1.08 million genome-wide SNPs from 164 individuals representing thirteen Juniperus lineages with phylogenomic datasets comprising 3,381 nuclear single-copy genes and nearly complete plastomes. We detected extensive phylogenomic discordance and cytonuclear incongruence across genomic datasets. Topology weighting, coalescent simulations, quartet-based tests, and analyses of gene flow and reticulation collectively support the interpretation that these patterns were shaped by the combined effects of prolonged incomplete lineage sorting and gene flow during lineage diversification. Ecological niche analyses further provide a spatial and climatic context in which environmentally similar lineages may have had greater opportunities for secondary contact during historical range shifts. Collectively, our results reveal that the evolutionary history of Qinghai-Tibet Plateau Juniperus is characterized by reticulate diversification rather than strictly bifurcating evolution, and demonstrate how genome-wide discordance can provide biological insights into the evolutionary processes underlying lineage diversification.
Gene Flow↗
Admixture and Selection Driven by El Niño-Southern Oscillation Events Shape the Genetic Structure of Octopus mimus-O. hubbsorum Complex Across the Humboldt and South Equatorial Current Transition Zone.
Marine transition zones, where contrasting water masses converge, can function as natural laboratories for studying admixture and early stages of speciation. The genomic structure of the eastern Pacific Octopus mimus-O. hubbsorum complex was investigated by analyzing whole-genome sequencing data from 67 individuals sampled along the west coast of the Americas, spanning Mexico and the Peruvian coast. This includes the South Equatorial Current, the transition zone, and the Humboldt Current System. The mitochondrial genomes fell into two major genetic clades that largely corresponded to the warm-water northern (O. hubbsorum) and cold-water southern (O. mimus) lineages. Analyses of the nuclear genomes revealed the same bipartite structure but also identified a broad admixture zone characterized by two different admixed clades (Admixed-Cold and Admixed-Warm). The results suggest that episodic relaxation of oceanographic barriers during El Niño-Southern Oscillation (ENSO) events promotes secondary contact and gene flow, resulting in admixed individuals recurrently during ENSO years. However, the survival of these admixed individuals depends on the adaptive genetic composition of each organism and the prevailing environmental conditions. Outlier SNP analysis supports these findings, where the Admixed-Cold cluster shares mainly the adaptive genetic component identified as outliers in O. mimus, while Admixed-Warm is linked to those in O. hubbsorum. The O. mimus-O. hubbsorum complex is currently occupying a gray zone of speciation, in which selection and climate-driven connectivity act in tandem to shape genomic divergence.
gene flow↗
Biogeographic Structure and Mitonuclear Discordance Reveal Cryptic Diversity in Pacific Herring (Clupea pallasii).
Forage fishes are biological drivers throughout the Pacific Ocean, from the Arctic to nearly subtropical latitudes. As a critical trophic link, the health and stability of Pacific herring (Clupea pallasii) populations have implications for other marine species, including several targeted by large, productive fisheries. Previous research has indicated marked divergence between Pacific herring in the Bering Sea and the Gulf of Alaska. Seeking to localize this biogeographic break, we generated low-coverage whole genome resequencing data for 120 Pacific herring from seven sites across the northern Gulf of Alaska and the eastern Bering Sea and Aleutian Islands. Single nucleotide polymorphisms across the mitogenome (267) and nuclear genome (~5.6 million) corroborate a biogeographic break in Pacific herring along the Alaska Peninsula and Aleutian Islands, as far west as Unalaska. We identified two distinct populations: one exists along the northern coasts of the Aleutian Islands and in the eastern Bering Sea; the other occupies the southern edge of the Aleutians and the Gulf of Alaska. Two mitochondrial haplogroups co-occurring across the Gulf of Alaska suggest secondary contact between two populations, likely representing glacial refugia. Our results underscore the importance of geological events to contextualize the diversification of forage fish species.
Bering Sea↗
Hidden genomic structure and widespread structural polymorphism across environmental gradients in the spiny sea star Marthasterias glacialis.
Genomic regions of reduced recombination can preserve linkage among co-adapted alleles, facilitating local adaptation despite high connectivity. Such regions-often generated by chromosomal inversions-may be especially important in highly dispersive marine taxa yet remain poorly documented in echinoderms. Here, we combined a chromosome-level reference genome with genome-wide ddRAD-seq from 296 Marthasterias glacialis individuals across 19 Atlantic-Mediterranean locations to quantify population structure and scan for recombination-suppressed haploblocks. Genome-wide neutral markers showed significant population differentiation together with evidence of high connectivity, revealed by the presence of inter-ecoregion migrants. Additionally, we identified 16 polymorphic haploblocks with patterns consistent with putative chromosomal inversions spanning 18.6% of the genome. Haploblock haplotypes were strongly environmentally and geographically structured and contained genes with key functions in stress response, osmoregulation and thermal tolerance. Haplotype distributions also paralleled previously described mitochondrial lineages despite nuclear gene flow, consistent with a model of ancient divergence followed by secondary contact. Overall, our results suggest a role for widespread structural polymorphism in adaptive differentiation in Echinodermata, providing a framework for linking echinoderm genome rearrangements to ecological divergence. Marthasterias glacialis thus emerges as a promising system to explore how structural variation contributes to adaptation and genome evolution in highly dispersive organisms.
Animals↗
Phylogenomic evidence provides insights into the phylogeny and speciation patterns in the subgenus Caloscordum (Allium, Amaryllidaceae).
Phylogenomics with abundant informative sites offers a powerful means for elucidating complex diversification history. Here, we collected 22 samples from 18 populations representing all species of subgenus Caloscordum (Allium). Using transcriptome and whole-genome resequencing data, we generated 1755 low-copy nuclear genes and 81 plastid genes. By integrating morphological and phylogenomic evidence, we clarified the subgenus's complex evolutionary histories and speciation patterns. A total of 18 morphological characteristics were analysed, with a taxonomic framework established. Our analyses resolved robust species relationships despite detecting extensive phylogenetic discordances, which were attributed to incomplete lineage sorting (ILS) and hybridization. Specifically, our results suggest that A. inutile originated via rapid budding speciation from the widespread A. tubiflorum. This process likely coincided with mid-Pleistocene glacial-interglacial cycles and may have been reinforced by geographic isolation and ecological adaptation. In contrast, the sole tetraploid species, A. peikingense, was confirmed to be of hybrid origin, derived from A. neriniflorum and A. tubiflorum. This allopolyploidization event appears to have been facilitated by secondary contact between the parent species, which was likely associated with climatic oscillations within the 35° N-45° N arid belt. Overall, our findings elucidate the intricate speciation patterns within Caloscordum and highlight how the interplay of polyploidization, ecological isolation, and tectonic uplift-driven aridification has shaped plant diversity in East Asia.
Phylogeny↗
Altered intestinal fluid movement in response to Trichinella spiralis in immunized rats.
Net intestinal fluid movement was measured in immunized and non-immunized rats infected with the enteric stages of the nematode, Trichinella spiralis. Animals were studied 30 min, 5 days and 30 days after receiving infective larvae. Net water movement across the mucosal surface of the gut was measured in vivo by perfusing a cannulated segment (approximately 30 cm) of proximal small intestine with an isotonic solution containing a nonabsorbable marker, 14C polyethylene glycol, at a rate of 0.5 ml/min. Uninfected rats showed net absorption of water, 25 microliter/h per cm of intestine. This response was unaltered when rats were infected (7 x 10(3) larvae/rat) and examined 30 minutes later. Five days after primary infection net tissue-to-lumen fluid movement, ie. net secretion, occurred at a rate of 45 microliter/h per cm. When rats were studied 30 days after primary infection, net absorption equivalent to the preinfection level was observed once again. Previously infected (immunized) rats, when challenged (secondary infection, 7 x 10(3) larvae/rat) and examined within 30 min showed a significant decrease in net absorption rate as compared with non-immunized rats. Absorption returned to the preinfection level at both 5 and 30 days post challenge. Results support the conclusion that T. spiralis caused a decrease in net lumen-to-tissue fluid movement during primary and secondary infections. The response was initiated faster in previously infected hosts. The rapid induction of net fluid movement in the direction of secretion upon secondary contact with the parasite is associated temporarily with prevention of worm establishment.
Absorption↗
Are We Witnessing a Speciation Continuum? Evidence From Current and Past Gene Flow in the Genus Oritrophium s.s. (Asteraceae) From the Tropical High Andes.
Determining species boundaries is key for appropriately assessing biodiversity. However, the continuity of the speciation process makes delimiting species a difficult task, especially for recently diverged taxa. Furthermore, past introgression may leave traces that result in reticulate evolutionary patterns, challenging the estimation of species relationships. The fastest-evolving biodiversity hotspot on Earth is the Páramo. Its flora in the tropical high Andes is known for extraordinarily high species richness and endemism. However, the recent origin, fast diversification and complex taxonomy of many genera challenge species delimitation and phylogenetic reconstruction. In this study, we reconstructed phylogenetic relationships and addressed the role of introgression in the diversification of Oritrophium s.s. (Asteraceae) based on phylogenomic data. We combined genomic, phenotypic and ecological data to test species boundaries and compared trajectories across the speciation continuum within the taxonomically complex 'O. peruvianum group'. We found that historical introgression played an important role in the evolution of Oritrophium s.s., and many of the taxa within the 'O. peruvianum group' are at various stages of speciation. These results highlight the importance of testing for introgression to understand the diversification of recently evolved groups. Likewise, they suggest that heterogeneous speciation trajectories associated with geographic isolation and secondary contact, possibly during the Pleistocene, contributed to plant diversity in the tropical high Andes.
Genetic Speciation↗
Mapping Species Birth Across the Recombination Landscapes of Marine Snails.
Understanding the drivers of heterogeneous genomic divergence is essential for uncovering the mechanisms that generate and constrain biodiversity. The extent to which adaptation and speciation are facilitated by reorganisation of the recombination landscape remains untested in many systems. Marine ecosystems, with their dynamic and fluid habitats, offer a compelling context to investigate genomic divergence. In this study, we mapped genomic divergence and selection across recombination landscapes of parapatric marine snail sister species that we show have recently undergone secondary contact. Regions of reduced recombination were enriched for genes exhibiting signatures of negative selection, whereas regions of high recombination were associated with genes under putative positive selection. Notably, the recombination landscape of the population in parapatry of one species (Scurria viridula) differs markedly from that of the other population within this same species, highlighting the role of introgression in reshaping recombination landscapes. In the other species (Scurria zebrina), conservation of the recombination landscape and divergent selection among populations suggest trapping of beneficial allele combinations in regions of low recombination maintains the identity of this species. Among species, signals of divergence with gene flow consistently cluster within specific genomic regions characterised by high recombination rate variation among the populations of S. viridula. These results challenge traditional theoretical expectations of recombination evolution by showing that the causes of genomic divergence can be population-specific. This study demonstrates that recombination landscapes are key modulators of genomic divergence, with contemporary evolutionary shifts that could enable populations to adapt to distinct environments. Our findings provide new insights into the interplay between recombination, selection, and gene flow during speciation, underscoring the complexity of evolutionary trajectories in marine systems.
Genetic Introgression↗
Ancient Introgression Explains Mitochondrial Genome Capture and Mitonuclear Discordance Among South American Collared Tropidurus Lizards.
Mitonuclear discordance-evolutionary discrepancies between mitochondrial and nuclear DNA phylogenies-can arise from various factors, including introgression, incomplete lineage sorting, recent or ancient demographic fluctuations, sex-biased dispersal asymmetries, among others. Understanding this phenomenon is crucial for accurately reconstructing evolutionary histories, as failing to account for discordance can lead to misinterpretations of species boundaries, phylogenetic relationships, and historical biogeographic patterns. We investigate the evolutionary drivers of mitonuclear discordance in the Tropidurus spinulosus species group, which contains nine species of lizards inhabiting open tropical and subtropical environments in South America. Using a combination of population genetic and phylogenomic approaches applied to mitochondrial and nuclear data, we identified different instances of gene flow that occurred in ancestral lineages of extant species. Our results point to a complex evolutionary history marked by prolonged isolation between species, demographic fluctuations, and potential episodes of secondary contact with genetic admixture. These conditions likely facilitated mitochondrial genome capture while diluting signals of nuclear introgression. Furthermore, we found no strong evidence supporting incomplete lineage sorting or natural selection as primary drivers of the observed mitonuclear discordance. Therefore, the unveiled patterns are most consistent with neutral demographic processes, coupled with ancient mitochondrial introgression, as the main factors underlying the mismatch between nuclear and mitochondrial phylogenies in this system. Future research could further explore the role of other demographic processes, such as asymmetric sex-biased dispersal, in shaping these complex evolutionary patterns.
Animals↗
Historical introgression as a driver of diversification of diploid Picris (Compositae) in the Mediterranean Basin.
The Mediterranean Basin is recognized as one of the world's most prominent biodiversity hotspots, where past climatic changes have driven range shifts, secondary contact between populations, and gene exchange. This study investigates the impact of historical introgression on the diversification of diploid members of the genus Picris (Compositae). Using nuclear and plastid genome data obtained through the Hyb-Seq approach, we assess whether introgression contributed to the evolution of the Mediterranean Picris, potentially giving rise to multiple regional endemics. We also test whether introgression was associated with the transfer of traits such as life strategy and fruit morphology, which are involved in habitat-specific adaptation. Phylogenetic network analysis revealed two major introgression events that shaped evolutionary trajectories within the genus. The earliest and most complex events involved the Turkish endemic P. campylocarpa, which hybridized with the most recent common ancestor (MRCA) of the P. cyprica-P. pauciflora lineage and with the MRCA of the B1 subclade, comprising the P. hieracioides group and the P. scaberrima-P. strigosa lineage. The latter introgression preceded shifts from iteroparity to semelparity and from heterocarpy to homocarpy, ruling out an adaptive introgression origin for these traits. Nevertheless, all detected historical introgression events contributed to the diversification of diploid Picris taxa.
Diploidy↗
Introgression among maternal lineages inferred from complete mitogenomes and molecular dating helps resolve phylogeography of European roe deer.
BACKGROUND: The European roe deer (Capreolus capreolus) is one of the most widespread ungulates in Europe, with a phylogeographic structure mainly shaped by Pleistocene glacial cycles and secondary contacts with the Siberian roe deer (C. pygargus). METHODS: We sequenced 52 complete mitogenomes of C. capreolus from Slovenia, Poland and France, and combined them with 24 publicly available sequences of C. capreolus and C. pygargus, yielding an alignment of 76 genomes representing 59 haplotypes (42 from C. capreolus and 17 from C. pygargus). Phylogeographic structure was assessed using a median-joining network, and divergence times were estimated using a time-calibrated Bayesian phylogeny based on mitochondrial coding regions, incorporating published ancient C. pygargus mitogenomes. We additionally screened mitochondrial protein-coding genes for selection. RESULTS: The haplotype network recovered the three major European roe deer clades (Eastern, Central, and Western) and detected Central-clade haplotypes in France. Two Polish haplotypes (Cp9 and Cp10), detected in C. capreolus, clustered within the C. pygargus mitochondrial lineage, supporting mitochondrial introgression. Time-calibrated phylogenies placed introgressed haplotypes within established C. pygargus lineages. Selection analyses provided limited evidence for episodic positive selection restricted to a small number of codons. CONCLUSIONS: Whole mitogenomes improve resolution of roe deer phylogeography and reveal introgressed maternal lineages, while time-calibrated phylogenies and selection tests add evolutionary context for interpreting mtDNA diversity in genus Capreolus.
Animals↗
[Characteristics of the outbreak and control of an epidemic of bacillary dysentery of hydric origin].
In December 1978, an unexpected outbreak of acute gastroenteritis occurred in a shoe factory. The clinical, epidemiological and laboratory investigations established the hydric origin of the dysentery due to Shigella flexneri 3 a, caused by the illicit communication of the drinking water and industrial water mains. The antiepidemic measures promptly taken arrested the outbreak in three days ; there were no secondary, contact cases.
Adult↗
Comparison of microbial counts on beef carcasses by using the moist-swab contact method and secondary tissue removal technique.
When a tissue removal rinse technique was compared to the moist-swab contact method, significantly greater numbers of bacteria were recovered from beef carcasses, especially when the flora exceeded log10 4.5/6.45 cm2. Secondary treatment of the removed surface tissue by blending resulted in a significantly greater number of bacteria being recovered than when the same sample was swabbed and/or rinsed. Data indicate that blending of the carcass surface tissue provides a more representative value of the true microbial flora.
Animals↗
Spread of Haemophilus influenzae. Secondary illness in household contacts of patients with H influenzae meningitis.
To determine the risk of severe secondary illness in household contacts of patients with Haemophilus influenzae meningitis, telephone interviews were conducted with contacts of patients with reported cases. Four probable or proved secondary cases of severe disease were identified for a secondary attack rate of 0.4%. The secondary attack rate for household contacts of patients 2 years of age and younger was 4.9%. Until safe, effective prophylactic measures become available, physicians should explain to parents that any person who becomes ill in the month after a household case of H influenzae meningitis should be brought to the attention of a physician for appropriate evaluation and treatment.
Child, Preschool↗
Acute eye disease secondary to contact-lens wear.
In a three-month survey of some hospital consultant ophthalmic services, 82 instances of complications of contact-lens wearing were reported. Some of the complications gave rise to discomfort, but in only 5 cases was vision impaired.
Acute Disease↗
Haemophilus influenzae meningitis. A national study of secondary spread in household contacts.
To determine the risk of severe Haemophilus influenzae illness among household contacts of patients with H. influenzae meningitis, we studied prospective data obtained in 19 states from January 1, 1977, to June 30, 1978. H. influenzae meningitis was reported in 1403 patients, and 1147 (82 per cent) of the exposed families were investigated for the occurrence of H. influenzae disease within 30 days after its onset in the index patient. During this interval, nine of 1687 household contacts (0.5 per cent) under the age of six years had systemic disease confirmed to be caused by H. influenzae Type b. The risk in children less than one year of age was 6 per cent, and the risk in those less than four years of age was 2.1 per cent. None of 2624 contacts above the age of five was affected. In the 30 days after onset of meningitis, the risk of this infection alone, aside from other types of serious H. influenzae disease, is 585 times greater in household contacts than the age-adjusted risk in the general population. The risk of H. influenzae disease in household contacts under six years of age is similar to the risk of secondary meningococcal disease in all household contacts--indicating a need for effective antimicrobial prophylaxis.
Adolescent↗